Automotive brake switch

ABSTRACT

An automotive brake switch including a body having a linearly traveling profiled carriage which makes or breaks various circuits as the carriage travels. The switch includes a plunger which, at first, is free to move relative to the carriage, but upon installation is locked to the carriage. A rotatable lever arm holds the carriage in a desired neutral operating position, and maintains free movement of the plunger relative to the carriage. When the switch body is installed, the plunger comes into contact with an arm of the brake which causes the brake to move against the force from a spring to assume a desired adjustment position relative to the carriage for proper operation. The rotatable lever arm is turned to lock the plunger to the carriage and to free the carriage for travel within the body. Thereafter, the carriage responds to movement of the plunger caused by the brake arm to make and break circuits in the normal fashion to control the operation of cruise control, stop lamps, etc. Also, the length of the carriage is somewhat less than the space provided in the switch body. This permits overtravel of the carriage within the body without causing readjustment.

FIELD OF THE INVENTION

The present invention relates in general to automotive switches, and inparticular to a brake switch which automatically self-adjusts uponinstallation in a vehicle.

BACKGROUND OF THE INVENTION

There are many situations, particularly in the automotive industry,where the proper operation of signals, the action of vehicle components,and even the safety of an operator are dependent upon precise timing andactuation of electrical switches. For example, reliable operation ofswitches which control the operation of power brakes, the energizationof stop lamps, the disconnection of cruise control, and the energizationof various warning and indicator lights, is critical in maintainingoperator safety. When such switches are maladjusted, either duringfactory installation or by operator action, a hazardous condition canresult. Also, even in the event that the maladjusted switch does noteffect operator safety, vehicle battery failure may occur when lightssuch as stop lamps remain energized at all times.

The construction and proper installation of such switches, andrecognition of their importance for safety and other reasons are,therefore, well understood. The nature of the automotive manufacturingbusiness is such, however, that all components including the switchesare most efficiently installed and adjusted at optimum workingconditions in the factory, as the vehicle is assembled. Later handlersof the vehicle such as retail dealers frequently have neither theequipment nor the skilled personnel needed to accomplish the job as wellas it can be done in the factory.

Even at the factory, however, it is preferred to have standardadjustments made rather than leaving the adjustments to the individualmanual skills of the assembly line worker. For example, to adjust forappropriately timed switch actuation in the prior art, an assembly lineworker installed the switch and then pulled upon the brake pedal to pushin a plunger and set the position of the plunger for operation. Sincethe size and strength of the worker installing the switch varied, thereprobably resulted an over-adjustment or under-adjustment depending onthe strength of the person that installed the switch.

Also, even if the prior art brake switches were installed and adjustedcorrectly at the factory, a vehicle operator could accidentallyover-adjust the switch by hooking a foot under the brake pedal. Whenthis occurred, the brake lights would remain on, the battery would godead, or switch components could be damaged. The operator would thenhave to bring the vehicle to a dealer to readjust or replace the switch.

Accordingly, there is a need in the art for an automotive switch,particularly an automotive brake switch, which is self-adjusting, andwhich may not be inadvertently readjusted or damaged by upward movementof the brake pedal.

OBJECTS OF THE INVENTION

Thus, a primary object of the present invention is to provide anautomotive switch which requires little if any individual adjustment onthe assembly line or in later use.

Another object of the present invention is to provide a switch whicheliminates the possibility of damage or readjustment resulting fromovertravel of the switch components when the brake pedal is forcedupward.

A further object of the invention is to reduce the cost and difficultyof assembling delicate parts in a vehicle.

A still further object of the present invention is to reduce the costand improve the quality of vehicles as delivered to a customer.

These and other objects of the present invention will become apparentfrom a review of the description provided below.

SUMMARY OF THE INVENTION

The present invention is organized about the concepts of: (1)automatically and uniformly setting the switch in its normal operatingposition upon installation, and (2) preventing inadvertent loss ofadjustment or damage of the installed switch. The switch of the presentinvention includes a body having a linearly traveling profiled carriagewhich makes or breaks various circuits through movable contacts on theswitch body as the carriage travels. The switch also includes a plungerwhich, at first, is free to move relative to. the carriage, but uponinstallation is locked to the carriage, and a rotatable lever armadjacent to the carriage and the plunger.

The rotatable lever arm holds the carriage in its desired neutraloperating position at which it will normally remain. In this neutraloperating position, the plunger is free to move relative to thecarriage, and is lightly spring biased into its most extended position.When the switch body is installed, the plunger comes into contact withthe brake arm which causes it to move against the force from the springto assume a desired adjustment position relative to the carriage forproper operation.

Next, the rotatable lever arm is turned, first to lock the plunger tothe carriage, and then to free the carriage for travel within the body.Thereafter, the carriage responds to movement of the plunger caused bythe brake arm to make and break circuits in the normal fashion tocontrol the operation of cruise control, stop lamps, etc. The operatingposition of the carriage relative to the switch body is maintainedwithout further change.

Also, the length of the carriage is somewhat less than the spaceprovided in the switch body. This permits overtravel of the carriagewithin the body without causing readjustment. Thus, when the brake pedalis inadvertently forced upward, the plunger merely forces the carriagebackward into the overtravel space without readjusting the position ofthe plunger relative to the carriage or damaging the switch components.

BRIEF DESCRIPTION OF THE DRAWING

For a better understanding of the present invention, together with otherobjects, features and advantages, reference should be made to thefollowing description of the preferred embodiment which should be readin conjunction with the following figures wherein like numeralsrepresent like parts:

FIG. 1: is a side plan view of a brake pedal assembly showing thearrangement of a preferred switch according to the present inventionrelative thereto.

FIG. 2: is an exploded view of a preferred switch according to thepresent invention.

FIG. 3: is an end view of a switch according to the present inventionshowing the position of the lever arm handle prior to installation.

FIG. 4A: is a sectional view of a switch according to the presentinvention as installed in a vehicle with the brake pedal in the at restor "off" position.

FIG. 4B: is a sectional view of a switch according to the presentinvention as installed in a vehicle with the brake pedal in the appliedor "on" position.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the drawing, there is shown the arrangement of apreferred switch 1 according to the present invention relative to abrake pedal arm 2. As shown, the switch 1 is mounted to a switchmounting plate 3 which is securely fixed to a console panel 4. Althoughmany variations are possible, the preferred mounting plate includes abase portion 5 with a perpendicularly extending mounting flange 6 forreceiving a rotatable sleeve 13 of the switch 1.

For mounting the switch to the mounting plate, the rotatable sleeve 13is provided with projecting tangs 53, shown particularly in FIG. 2. Thesleeve is inserted into an opening in the mounting flange 6 and rotatedso that the projecting tangs rest against the exterior 90 of themounting flange 6. Thus, the mounting flange is captured between theprojecting tangs 53 and the wall 91 (FIG. 2) of the switch body tosecurely fix the switch to the mounting plate.

Fixed to the brake arm 2 is a striker plate 74 which is in pressingengagement with plunger 16 of the switch 1 when the brake pedal 2 is inan at rest (brakes off) position. As will be described in more detailbelow, the plunger 16 extends into the switch body 14 through sleeve 13and compression spring 20 (FIG. 2). The spring 20 is coupled about thehead 17 of the plunger to bias the plunger head 17 into contact with thebrake arm striker plate 74 under a relatively light force, i.e., on theorder of 2 lbs.

As is known, upon application of pressure to the brake pedal 11, i.e.,when the brakes are "on", the brake arm 2 rotates about the fixed pin 7in the direction of arrow 8. The rotation of the brake arm causes linearmotion of master cylinder rod 9 through the vehicle fire wall 10 andinto the master cylinder 12 to operate the vehicle brakes. The strikerplate 74 rotates with the brake arm away from the plunger 16 which isurged under the force spring 20 to travel linearly outward from theswitch body.

When pressure is removed, the brake arm rotates back to its at rest or"off" position in the direction of arrow 73, and the striker plate 74forces the plunger back into the switch body 14. The linear travel ofthe plunger 16 causes linear travel of a carriage within the switch bodywhich makes and breaks connections between switch arms and associatedcontacts to appropriately energize and deenergize vehicle components 72(e.g. stop lamps, cruise control, motor control circuitry, etc.) throughthe vehicle battery 73.

The details of the switch 1 according to the present invention will nowbe described in connection with the exploded view thereof provided inFIG. 2. As shown, the switch body 14 houses a movable carriage 15 whichhas three major sections: a body section 81, a slotted cylindricalsection 82, and a switch arm contacting section, 83. The switch armcontacting section 83 includes a slot 84 along the length thereof whichslidingly engages projecting tabs 85,86 on the interior of the switchbody 14. The mating of the slot 84 and the projecting tabs 85,86 ensuresproper positioning of the carriage 15 within the body while allowing thecarriage to slide linearly along the length of the projecting tabs85,86.

The plunger 16 extends into the body through sleeve 13 and spring 20,and, prior to installation of the switch into the switch mounting plate3 (FIG. 1), is loosely telescopically positioned within the opening 47in the slotted cylindrical section 82. A C-clamp 91 surrounds theslotted cylindrical section with the plunger positioned therein. TheC-clamp 91 is initially maintained in an open position to allow theplunger to move axially within the slotted cylindrical section 82. Uponinstallation, however, the C-clamp is closed to fix the position of theplunger relative to the carriage.

Prior to installation of the switch to the mounting plate, the carriage15 is locked into a desired neutral position in the body 14 by lever arm23. The lever arm is retained in openings 55 of the switch body inparallel relationship with the carriage 15 and plunger 16, and isrotatable within openings 55 by twisting of lever arm handle 93 which ispositioned outside of the switch body for convenient access.

The pre-installation position of the lever arm handle 93 is as shown inFIG. 3. With lever arm handle in this position, a first radial extension61 of the arm 23 releasably engages slot 94 in the body section 81 ofthe carriage. In this manner, the carriage is securely maintained in adesired neutral position within the body for installation. At the sametime, a second extension 63, also extending radially from the lever arm23, removably extends between flanges 95 of the C-clamp 91 to hold theC-clamp in open position and maintain the freedom of movement of theplunger within the slotted cylindrical section 82 of the carriage. Thus,prior to installation, the plunger 16 is biased into its most extendedposition by spring 20, but is free to travel linearly relative to theslotted cylindrical section of the carriage upon application of forcesufficient to overcome the spring force, i.e., preferably about 2 lbs.At the same time, the carriage is held in a stationary position withinthe switch body by the releasable engagement of extension 61 and slot94.

During assembly of the vehicle, the switch is mounted to the mountingplate, as described above, by locking the mounting flange between theprojecting tangs 53 of the sleeve and the wall 91 of the switch body. Asthe switch is mounted in this fashion, the plunger pressingly engagesthe striker plate 74. Since the C-clamp 91 is maintained in an openposition by extension 63 of the lever arm, the plunger moves axiallyinto the cylindrical slotted section 82 of the carriage.

When the mounting of the switch to the mounting plate is complete, thelever arm handle 93 is simply rotated in the direction of arrow 100(FIG. 3). This action first causes disengagement of the lever armextension 63 from between the C-clamp flanges 95. As a result, theC-clamp closes tightly around the cylindrical slotted section 82 withthe plunger extending therein to fix the relative positions of theplunger and the carriage. Continued rotation of the lever arm causesdisengagement lever arm extension 61 from the slot 94, thus freeing thecarriage for linear movement within the switch body to make or breakswitch contacts.

Advantageously, the switch according to the present invention completelyobviates the disadvantages associated with prior art adjustmentprocedures since proper installation is not dependent upon the strengthof the installer. As discussed above, the former practice was to installthe switch and then pull upward on the brake pedal to force the plungerinto a carriage within the switch housing. Thus, depending upon thestrength of the installer, the adjustment of the plunger relative to thecarriage varied. Oftentimes, improper adjustment of the switch resultedfrom this procedure causing malfunction of the switch.

With the switch of the present invention, adjustment of the position ofthe plunger within the cylindrical slotted section is accomplished inthe act of mounting the switch to the mounting plate. The installer needonly apply enough force in pressing the head 17 of the plunger againstthe striker plate to overcome the spring force and cause the plunger toextend into the cylindrical slotted section of the carriage. Once theswitch is installed to the mounting plate 3, the lever arm handle isrotated to optimally fix the position of the plunger relative to thecarriage. Uniform adjustment is thus achieved regardless of operatorstrength.

Turning now to FIGS. 4A and 4B, the switch of the present invention isshown in two positions. The first, FIG. 4A, shows the switch with thebrake pedal in an at rest or "off" position. In FIG. 4B, the switch isshown in its position when the brake pedal is in the down position andthe brakes are applied or "on". Although a variety of switchingarrangements could be provided, in the preferred embodiment three buttcontacts 32, 34 and 36 are included in the switch body with associatedswitch arms 41, 39, and 43, respectively. The butt contacts may beelectrically connected to the vehicle battery, and the switch arms toselected vehicle components/circuits, or vice-versa. For example, theswitch arm 41 may be electrically connected to an engine controller, theswitch arm 39 may be connected to a speed controller, and the switch arm43 may be connected to the stop lamps.

The switch arm contacting section 83 of the carriage is profiled to formsloping cams, the cams 31, 33, and 35 being typical. With axial movementof the carriage within the housing, the cams pressingly engage theswitch arms and the butt contacts. In FIG. 4A, with the brakes in the atrest or in the "off" position, it may be seen that the cam 31 is not incontact with switch arm 39 associated with butt contact 34. The cam 33is similarly out of contact with switch arm 41 associated with buttcontact 32. The cam 35 is in contact with switch arm 43, thus openingthe connection between the switch arm 43 and butt contact 36 and, forexample, deenergizing the stop lamps.

In FIG. 4B, the switch is shown with the brakes applied or in the "on"position. When the brakes are applied, the plunger moves outwardly fromthe switch body under the force of spring 20. The carriage slideslinearly within the switch body toward wall 91 causing engagement anddisengagement of the cams and switch arms. As shown, with the brakesapplied or in the "on" position the cam 31 is in contact with switch arm39 associated with butt contact 34, and the cam 33 is in contact withswitch arm 41 associated with butt contact 32, thus opening buttcontacts 34 and 32. The cam 35 is out of contact with switch arm 43,thus closing butt contact 36 and, for example, energizing the stoplamps.

Referring again to FIG. 4A, a particularly advantageous aspect of thepresent invention may be seen. The switch body of the present inventionis sized to provide an overtravel protection space 101 between the end102 of the carriage and the interior 103 of the end wall 104 of theswitch body. In prior art designs, no such overtravel protection spaceis provided. When the brake pedal in these prior art designs is pulledupward (i.e. in the direction of the arrow 105 in FIG. 1) to adjust theswitch, or is inadvertently pulled upward by the operator's foot, damageor readjustment of the switch can occur from the plunger forcing thecarriage against the back wall of the switch housing.

The overtravel protection space 101 of the present invention providesprotection for inadvertent or intentional upward movement of the brakearm. When the brake arm is pulled backward, the plunger forces thecarriage toward the rear wall and into the overtravel protection space101. The space 101 is sized to a width d, approximately 5 millimeters(mm) in the preferred embodiment, sufficient to account for any easilyachieved upward movement of the brake pedal. Thus, to the extent that anoperator could cause upward motion of the brake pedal without destroyingor bending the brake arm and connected components, the overtravelprotection space 101 is sufficiently sized to receive the end 102 of thecarriage. The carriage, therefore, cannot be forced into the rear wall104 of the switch body absent the application of some extraordinaryforce. This eliminates the problems of readjustment and damage caused inprior art switches as a result of upward motion of the brake arm.

Thus, according to the present invention there is provided an automotiveswitch which is self-adjusting, allowing facile and uniform adjustmentupon installation. The adjustment is performed by the interaction of arotatable lever arm which allows free movement of the plunger withrespect to a stationary carriage prior to installation. Uponinstallation, the lever arm is rotated to fix the relative positions ofthe plunger and carriage, and to release the carriage for linearmovement. In addition, the present invention includes an overtravelprotection space for protecting against damage or readjustment caused byupward movement of the brake arm.

The embodiments which have been described herein, however, are but someof the several which utilize this invention and are set forth here byway of illustration but not of limitation. For example, the spring 20could be installed in a variety of locations to achieve appropriatebiasing. Also, the rotatable lever arm, the carriage, and the plungercould be arranged in a variety of ways to achieve the relative lockingprovided by the lever arm as described. It is obvious that many otherembodiments, which will be readily apparent to those skilled in the art,may be made without departing materially from the spirit and scope ofthis invention.

What is claimed is:
 1. A switch for making and breaking circuits in avehicle in response to movement of the brake of said vehicle betweenactive and rest positions comprising:a switch body, a movable carriagedisposed in said body, at least one set of electrical contacts mountedon said body adjacent to said carriage, said contacts being electricallyconnected to at least one of said circuits of said vehicle, saidcarriage being movable relative to said body causing making and breakingof said circuit in accordance with the position of said carriagerelative to said body; a striker plate fixed to said brake and movabletherewith; a plunger releasably connectable to said carriage to impartmovement thereto, said plunger being movable in and extending from saidbody with one end of said plunger being urged into contact with saidstriker plate; and a lever arm mounted for rotation in said bodyadjacent to said carriage and said plunger, having at least a radialextension for alternately engaging and releasing said carriage for axialmovement thereof in said body upon rotation of said lever arm.
 2. Aswitch according to claim 1, wherein said at least one set of electricalcontacts comprises a butt contact and a switch arm, and wherein saidmovable carriage is profiled to include at least one sloping cam, saidcam being positioned to pressingly engage said switch arm to make orbreak electrical connection between said switch arm and said buttcontact in accordance with the position of said carriage within saidbody.
 3. A switch according to claim 1, wherein said movable carriageincludes a slot therein, said radial extension releasably engaging saidslot to maintain said carriage in a fixed position within said body,wherein rotation of said lever arm releases said radial extension fromsaid slot to free said carriage for movement in said body.
 4. A switchaccording to claim 3, said switch further including a C-clamp forconnecting said carriage to said plunger, and wherein said lever armincludes a second radial extension engaging said C-clamp and maintainingfreedom of movement of said plunger relative to said carriage, whereinrotation of said lever arm releases said second radial extension fromsaid C-clamp to connect said plunger to said carriage.
 5. A switchaccording to claim 4, wherein rotation of said lever arm first releasessaid second radial extension from said C-clamp to connect said plungerto said carriage, and second releases said radial extension from saidslot to free said carriage for movement in said body.
 6. A switchaccording to claim 1, wherein said movable carriage includes acylindrical section, said plunger being movable in and extending fromsaid cylindrical section, and wherein rotation of said lever arm clampssaid plunger within said cylindrical section.
 7. A switch according toclaim 1, said switch further including a compression spring coupled tosaid plunger and biasing said plunger in an outward direction from saidswitch body and against said striker plate.
 8. A switch according toclaim 1, wherein said lever arm includes a lever arm handle disposedoutside of said switch body for rotating said lever arm.
 9. A switchaccording to claim 1, wherein said plunger is releasably connectable toa first end of said carriage to impart movement thereto, and wherein anovertravel protection space is provided between a second end of saidcarriage and an endwall of said switch body when said brake is in an atrest position.
 10. A switch in accordance with claim 1, wherein saidcarriage has a first end to which said plunger is connectable and asecond end which is spaced from an end wall of said switch body toprovide for overtravel protection.
 11. A switch according to claim 10,wherein said overtravel protection space is approximately 5 millimetersin width.
 12. A method of installing a switch for a brake in a vehicle,said brake including a brake arm and a striker plate fixed to said brakearm, said method comprising:providing a switch comprising:a switch body,a movable carriage disposed in said body, at least one set of electricalcontacts mounted on said body adjacent to said carriage, said contactsbeing electrically connected to at least one circuit of said vehicle,said carriage being movable relative to said body causing making andbreaking of said circuit in accordance with the position of saidcarriage relative to said body, a plunger releasably connected to saidcarriage to impart movement thereto, said plunger movable in andextending from said body and being spring biased in an outward directionfrom said body, and a lever arm having radial extensions mounted forrotation in said body adjacent to said carriage and said plunger,wherein rotation of said lever arm moves said radial extensions toconnect said plunger to said carriage and release said carriage formovement in said body; mounting said switch to said vehicle adjacentsaid brake arm with one end of said plunger contacting said strikerplate and being urged into said body; and rotating said lever arm toconnect said plunger to said carriage and release said carriage formovement in said body.
 13. A method of installing in a vehicle anautomotive brake switch comprising a body, a carriage disposed forlinear travel in said body, a plunger mounted on said carriage andnormally biased by relatively light pressure to extend therefrom, arotatable lever arm having radial extensions disposed on said bodyadjacent said carriage for locking said plunger to said carriage andfreeing said carriage for travel in said body comprising the steps ofinstalling said switch in said vehicle with said plunger in contact withsaid brake under pressure greater than said relatively light pressureand rotating said lever arm first to lock said plunger in fixed positionon said carriage and second to free said carriage for predeterminedlinear movement in said body.